* pac048h1321 4 ton ,r22,* freezing up , 25 low side 175 high side ,refrigerant charge 8 lbs what it calls for. after 1 min of running it is freezing up.It acts like it is low on freon but in you add more very little change in pressure. No suction filter on this unit , high side has muffler and dryerblower fan working. Compressor seems to be work OK. if you go by inlet air temp I should be running at least 70 on low side what should I check next?thanks for any help Ed

Has the system been opened prior to your coming to do work? If so, what was done? What is the metering device... TXV or piston?

Have you verified the evaporator coil is clean and there's very good air flow through the evaporator coil (no closed returns/supplies and clean filters). Any filter/dryer on the liquid line? If so, how old?

Best thought for the moment is there's some kind of obstruction. Where the freezing starts on the high side line will give you a clue as to where the obstruction might be, assuming it is an obstruction.

{capillary system} history on unit .Did the same thing about 2 years ago added freon to it to get pressure right worked great till 1 mo. ago service man came out said it was low on freon it has a leak some were but could not find one so he believed it was in the evaporator coil so he changed it same thing I think it may be the filter dryer but not sure . I know he should have changed the filter dryer but don't no why he didn't .It is freezing from the start of the capillary tubes then moves to the evaporator. {capillary's new with evaporator }

"...has a leak some were but could not find one so he believed it was in the evaporator coil so he changed it same thing".

When he was done replacing the evap. coil, were the pressures what you'd normally expect? Did the system run without freezing up or was there no improvement?

If yes to the above, he may not have found the true leak and you're still leaking R-22. Or without a new filter/dryer it is possible moisture/debris is causing the problems in the capillary tube although the pressures do seem normal for a system low on refrigerant.

My first suggestion is look for a leak near the condenser. Usually you can find a small oil stain. Look inside the condenser for signs of vibration wear and look at all braised connections. You might reclaim the R-22 and have it pressurized with nitrogen to determine if a leak still exists.

I hate to say you're low on refrigerant due to a leak but that's the best answer. If there's debris in the system, that could be a PITA to clean. Maybe get a new tech.

before he replaced the coil pressure was running 40 low 180 high side I have a filling it was not low but dryer filter restricted i wish he would haveweighted what he recovered before he put it back in this system holds 8 lbs . when he pulled it back out he had put 18 lbs. in it trying to keep it from freezing up with 18 lbs freon pressure where 50 to 55 low 200 high Yes need new tech. but under warranty now he thinks it is the compressor but if he don't change the filter I think I will have the some problem. and I have to wait a week or more before he can make it back out each time he comes out towork on it

If the filter/dryer was restricted you should see a high head pressure and lower than expected suction due to the restriction. Also you might see frost on the outlet side of the filter/dryer or at least notice a big temperature difference. Since both pressures are low it could be low R-22 or possibly a bad compressor. Without the high head you'll never see a high suction. And head pressure is a function of fluid and compression.